Mitsubishi Materials, ULVAC Develop Cu Alloy Sputtering Target for TFT

Mitsubishi Materials and Kanagawa based vacuum equipment maker, ULVAC, Inc. announced on Monday they developed new copper alloy sputtering target for wiring of thin film transistor of large screen liquid crystal panel. The new target could contribute to lower production cost for liquid crystal panel due to lower electric resistance than traditional aluminium wiring and no barrier metal layer with molybdenum and titanium. ULVAC processes alloyed materials from Mitsubishi group. They target 500 million yen of annual sales in 3 years.

They developed 2 types of target including copper-calcium alloy and copper-magnesium based alloy with calcium or aluminium. Mitsubishi Materials makes the alloy at Sakai plant with copper ingot supply from Naoshima smelter and the alloy from ingot to alloy at Onahama smelter. Mitsubishi Shindoh rolls the alloy into alloy flat product to supply for ULVAC.

Traditional thin film transistor uses aluminium target with barrier metal layer with high priced molybdenum and titanium to secure the bonding with glass substrate or foundation layer. Larger screen liquid crystal television needs better electric resistance and lower cost while traditional copper wiring has less bonding with substrate.

ULVAC developed technology to make oxygen mixture sputtering with better boding with substrate for copper alloy target. However, the firm found the technology has problem for the bonding during hydrogen plasma treatment. The firm and Mitsubishi Materials developed new copper alloy to solve the problem.

They expect aluminium target demand for thin film transistor grows to more than 1,000 tonnes in 2010. They expect copper wiring could replace 5% of the demand and the replacement could reach 30% in 2012.